.90 in a 1/8 scale unlimited?

[JimAllen]

Anyone put a .90 in a 1/8 scale hydro? I got a pretty good deal on a To-Be .90 Novarossi, so I bought it, and then I thought, this would be awesome in an unlimited style hydro. Is this a bad idea or is it reasonable? I ordered a kit from ML Boatworks, but I need to know if it's crazy or not. I have some .67 size engines to use if the .90 is a bad fit. I'll find a home for it one way or another.

 

[Hydro Junkie]

While a .90 would probably work, it would cause the following issues:

1)  To keep it from "over-revving", you would need to use an oversized prop

2)  Unless carefully balanced, the boat would be likely to blow over when running at much over half throttle due to the air being packed under the hull

3)  You would need to carry a larger fuel tank to accommodate the requirements of that thirsty engine

4)  It would not be legal for scale competition

Mike may have other things to say about this so I'd check with him as well

 

[Bradley Maglinger]

You just wouldn't be able to race in the 1/8 scale class in IMPBA. See Floridascaleboaters post below for Namba classes it is allowed in. No matter what have fun and Run it.

 

[Samuel Hagan JR]

I think it’ll work good. Like Brad said you won’t be able to run in scale competition 

 

[FloridaScaleBoater]

You just wouldn't be able to race in the 1/8 scale class.  However if it is for Fun and not racing, set it up and run it. 

Sure it would, F/X hydro or sport X in NAMBA

 

[Bradley Maglinger]

Rick you are correct it can compete in other classes, IMPBA 1/8 scale it would not be able to.   I will edit my first post thanks for getting the correct information out. 

Thank you,

Brad

 

[JimAllen]

Thanks for the replies guys, that gives me some things to consider. I am still not sure what engine I'll put in the 1/8 scale hull. I'm leaning towards a .67 now, as I hadn't thought about how much extra fuel I might need to carry to feed the .90. I haven't actually run one before. I don't know exactly/roughly how much additional fuel it would burn vs a .67 engine. I have 3 .90's and haven't put one in anything yet.I have a black head OPS, and older ringed Rossi marine .90 and the new Novarossi. Maybe I sould be looking at some plans for a .90 size rigger to play around with and learn the ropes a bit first.

 

[Mike Hughes]

Yeah Jim, go with the rigger. Over stuffing a boat with too much HP is fun for a moment. A boat you can drive and race is a lot better option for your time and money.

Mike

 

[brad nichols]

I think Zipp Kits have there JAE 90-101 rigger as a kit now and you won't be dis appointed  as it is cheap and simply to build. They have made a few changes from the original plans but that should only improve it. I make a cowl for the ones I have built.

 

[brad nichols]

 

[JimAllen]

I guess I need to call them to order the .90 size rigger, I don't see it listed on their site. I have built their .21 size and it was a piece of cake to put together. Easy to build makes sense, because you don't want a thousand hours build time in a race boat, it's gonna take a beating. I'd like to build one and run different motors just to get a feel for how the performance has changed from the old stuff to the new. How much fuel do you typically carry in a .90 sized boat?

 

[brad nichols]

Depends but 20to 24 should get you there,   I think there was a build article on the new 90 boat and I think I inquired about and it's around $130 for a short kit  I used 1/2" aluminum booms and the older design ran well with a 67 for power. They also have a 67-84 boat too.

Brad

 

[JimAllen]

Thanks Brad, I appreciate the info. I have some solid carbon rods I think I can use for boom rods, they were external fixation rods for broken bone scaffolding originally, now they'll get a second life in the fast lane. You'd be surprised at the expensive and exotic materials the medical device field throws away on a regular basis. I filled boxes with titanium and carbon fiber stuff headed for the scrap bin at my previous employer. I told everyone, "don't throw that stuff away! save it for me." I couldn't believe all that high quality material was going into a dumpster. Now I have a pretty solid supply in reserve. Thanks again for the tank volume info, and have a great weekend.

 

[brad nichols]

If you got it you mite as well use it. The price is definitely rite!

Brad

 

[DON MAHER]

Solid carbon rods are the only way to go on a rigger of any size!

 

[PaulHail]

Jim, I've chronicalling my (slow) JAE 91/101 kit build 





Go with 3/8" solid carbon booms, that's what the kit is designed for.  Don't know why they don't list the 91/101, but they make a nice reasonably priced kit and hardware.

 

[Andy Brown]

Jim,

Looks like you are going a different direction from your original thought, but I will make one point that solves the problem of too much power by putting a .90 in a .67 boat.

The Nova .91 does not change the weight and the power can be adjusted downward to be closer to the .67 by simply using less nitro. 20% nitro would be a great plan. Less cost and longer engine life.

 

[LohringMiller]

In NAMBA the X sport hydro class was often won by a larger engine in a scale boat that also competed in Sport 60.  Usually racers used engines that would easily interchange; that was often an 80, not a 90.

Lohring Miller

 

[Hydro Junkie]

Wouldn't it be possible to change out a 67 to a 90, or larger, if the engine mount was changed at the same time?  If mounted through the bottom of the hull, all you would have to do is remove the nuts holding down the mount and drop in the larger engine with it's mounts.  The only issue I see is having the room between the drive shaft and any structure in front of the engine making it too tight to get the engine in

 

[JimAllen]

Andy Brown and Lohring have some interesting ideas...especially since I'm new to this large scale stuff. I hadn't considered de-tuning a .90. I guess I have tunnel vision with regards to power, it's always,"how to get more". The idea of running a relaxed .90 is a great suggestion. I actually have a few different .90's, I even have an older, brand new, ringed Rossi marine .90 that's probably weight comparable to the Nova, but less maximized for power, since it's probably a few decades older. That might be a cool idea, and if I get confident enough to race, I can swap in a competitive .67 and not need a lot of mods, or race it in X and see how it and I do there. I have an old 15cc OPS blackhead too, but I think it might be a bit heavier, I actually haven't compared the weights of these engines, maybe I should look at that for a bit. Thanks for the great ideas. I have to get the boat built first, so I'll be thinking about how to manage the fuel payload for maximum engine versatility. It's always a pleasure to hear the ideas you guys have. Thanks again for all the input.